The present disclosure is related to a method of forming patterns of sub-optical lithographic dimensions using self-assembly of block copolymers, and articles thereof.
Block copolymers, consisting of two or more distinct homopolymers joined end to end, self-assemble into periodic microdomains having typical dimensions of 10 nanometers to 50 nanometers (nm). The possibility of using such microdomains to pattern surfaces has attracted increasing interest because of the expense and difficulty of patterning in nanoscale dimensions (especially sub-45 nm) using optical lithography.
Controlling the lateral placement of the block copolymer microdomains on the substrates continues to be a challenge. This problem has been previously addressed using lithographically pre-defined topographic and/or chemical patterning of the substrate. Previous studies have demonstrated that self-assembled block copolymer microdomains in form of lamellae can be directed to follow chemical patterning of the substrate, yielding periodicities close to those of the chemical pre-patterns. Other studies have shown that by controlling the surface wetting properties of the block copolymer on the bottom and side walls of a topographic pre-pattern, the lamellae can be directed to follow the topographic pre-pattern. The lamellae formed line/space patterns of smaller dimensions than the substrate pre-pattern, subdividing the topographic pre-pattern into a higher frequency line pattern; that is, a line pattern having a smaller pitch. One limitation of block copolymer patterning is the propensity of the patterns to form everywhere on the pre-pattern surface, for topographic and/or chemical guiding pre-patterns.
Thus, new methods are desired for forming self-assembled block copolymer nanopatterns having controlled lateral placement of the microdomains on the substrate.